Recent years have witnessed development of various types of flat-panel displays (hereinafter referred to as “FPD”).
In particular, an organic electroluminescence (EL) display device has been highly expected as an excellent FPD in terms of low power consumption and high-speed response, since it is capable of displaying an image by causing a luminescent layer, which is formed for each pixel, to self-emit light.
A pixel of an organic EL display device is typically constituted by a sub-pixel for a red (R) color including a luminescent layer that emits red light, a sub-pixel for a green (G) color including a luminescent layer that emits green light, and a sub-pixel for a blue (B) color including a luminescent layer that emits blue light. A luminescent layer provided in each pixel is a laminate of organic films. A pattern of a luminescent layer is formed for each sub-pixel.
As disclosed in Patent Literatures 1 and 2, a luminescent layer for each color is formed for each sub-pixel without causing color mixture, for example, by a deposition method with use of a mask (may also be called “shadow mask”).
In Patent Literatures 1 and 2, a pattern of a luminescent layer is formed for each sub-pixel by sequentially moving a mask and a substrate relative to each other.
A vapor deposition source and a mask are typically spaced apart from each other. As such, not only vapor deposition particles which enter an opening of the mask in a direction perpendicular to the opening, but also vapor deposition particles which enter the opening in a direction oblique to the opening are deposited onto the substrate.
In the case where the vapor deposition particles which enter the opening in the direction oblique to the opening are deposited onto the substrate, blurring, in which a thickness of the luminescent layer is gradually reduced toward an edge of the luminescent layer, is formed in an edge section of the luminescent layer. The formation of the blurred part causes deterioration, such as color mixture, in image display properties.
In view of the circumstance, a new deposition method (hereinafter referred to as “novel deposition method”) which can solve the above problem has been proposed. This is described with reference to FIG. 17.
FIG. 17 is a perspective view illustrating an arrangement of a vapor deposition device of the novel deposition method.
As illustrated in FIG. 17, (i) a vapor deposition source 160, (ii) a plurality of control plates 181, (iii) a mask 170, and (iv) a substrate 110 are provided in a hermetically-sealed vacuum chamber in this order in a Z axis direction so as to be spaced apart from one another.
The substrate 110 is moved (scanned) at a constant speed in a direction indicated by an arrow 110a in FIG. 17 while being spaced apart, by a predetermined distance, from the mask 170 which is parallel to the substrate 110. By carrying out deposition while moving the substrate 110 in this manner, it becomes possible to reduce a size of the mask 170 and thus prevent bending of the mask 170. The direction in which the substrate 110 is moved is a Y direction.
The mask 170 has a plurality of openings 171, a length direction of each of which corresponds to the Y direction. The openings 171 are formed in the mask 170 so as to be arranged in order along an X direction. The width of the mask 170 along the Y direction is smaller than the width of the substrate 110 along the Y direction.
Each of the control plates 181 has a main surface (surface having the largest area), which is parallel to a Y-Z plane. That is, each of the plurality of control plates 181 is perpendicular to the substrate 110. The plurality of control plates 181 are parallel to one another, and are arranged in order along the X direction.
The vapor deposition source 160 is provided so that a length direction of the vapor deposition source 160 corresponds to the X direction. The vapor deposition source 160 includes a plurality of nozzles 161 which are arranged in a row along the X direction.
Vapor deposition particles 191 injected from the nozzles 161 pass through between the control plates 181, and are transmitted through the openings 171 of the mask 170 so as to be deposited onto the substrate 110 which is being scanned. Providing the control plates 181 thus makes it possible to restrict oblique movement of the vapor deposition particles injected from the nozzles 161. That is, the provision of the control plates 181 makes it possible to restrict an incident angle of the vapor deposition particles entering the openings 171 of the mask 170. This makes it possible to suppress blurring of the luminescent layer deposited on the substrate 110.